Damper



Aug. 6, 1940. J. M. LARsoN 2,210,869

DAMPER Filed Nov. a, 1951 23 23 t ,L ,L z

INVENTOR John M. Larsom BY A9/WMM ATTORNEY Patented Aug. 6, 1940 UNITED[STATI-:s

PATENT. oFFlcs DAMPER Application November s, 1931, serial No. 173,344

4 Claims.

This invention relates to dampers and more particularly to the type ofdamper employing a plurality` of blades which are actuated together by across connection.

In order that the blades of a damper of this type may be opened andclosed together it has been customary to secure an actuating brackettoeach blade. 'I'hese actuating brackets are pivoted to a crossactuating member at a point so located relative to the blade that theactuating member will clear the blades in all the operative positions ofthe blade. It is common practice to use a at bar, pinned to eachactuating bracket, as the cross connection. A damper motor either.actuates the cross connection or is operatively connected to one of theblades by a mechanism apart from the cross connection.

'I'he difliculty encountered with this construction lies in the extremecare which must be employed in manufacture if proper operation is to beattained. Dampers of this type are generally built for a particularinstallation, making it impractical to tool up for quantity productionon a damper of certain dimensions. Consequently the parts areconstructed by hand and all dimensions must be laid out individually. Ifwith the usual stili' cross connection, one bracket is pivoted to thecross connection at a slightly greater distance from the damper pivotthan an adjoining damper. bracket, the pivot points of the brackets willmove through unequal distances, as the damper blades are moved from oneposition to another, thereby causing binding. Also, with the usual stiiicross connections, if the .brackets of all of thedamper blades are notparallel, binding will result. 'I'his binding throws additional load onthe damper motor and results in improper settingsv of the blades. Inaddition to the binding which resulted when dampers of this type werenot accurately constructed,'-the blades of such dampers would also notall close together unless extreme care was taken in the manufacture ofthe damper.' For instance, unless all of the brackets Were attached tothe cross connection at properly spaced points, one pair of blades wouldreach closed position before others of the blades, thereby preventingcomplete closure of the damper, which of course is objectionable in manytypes of installations. Also, in many instances, even through a damperof this type would be properly constructed at the factory, it would bebent or sprung while in transit from the factory to the job or duringinstallation, which would result in the damper then binding or failingto close completely.

An object of this invention is to provide a damper of the type employinga cross connection to actuate a plurality of blades in which the abovedifficulties are obviated.

A further object 0f the invention is to provide a damper comprising aplurality of blades operated simultaneously by a cross connection, ofsuch construction as to eliminate binding when shifting from one damperposition to another.

Another object is to provide a damper of the above mentioned type inwhich the blades may be readily adjusted during installation so thatthey all close together.

Another object is to provide a damper in which the degree of skill andcare that must be employed in manufacture and installation is reduced.

Other objects will appear from the following description and theappended claims. For a full disclosure of my invention reference is madeto the following detailed description and to the accompanying drawing inwhich:

Figure 1 is a plan view partly in section of a damper embodying theinvention,

Figure 2 is a perspective view showing an actuating bracket togetherwith a trunnon and a p'ortion of the actuating rod, and

Figure 3 is a sectional view through the bracket, trunnion and rod takenon line 3 3 of Figure 1.

The damper frame is generally illustrated at I0 and comprises arectangular frame of channel section adapted to be placed in a duct orthe like through which it is desired to control the now of air. Plvotedin frame I IJ are damper blades I I, I2, and I3 which when in theposition shown in solid lines in Figure 1 are eiective to close theopening inside the frame I0. The blades I I, I2, and I3 are similar andeach extends longitudinally across the opening. Rods I4, I5, and I 6 aresuitably secured to blades II, I2, and I3 and extend into holes drilledin frame I0 to form bearings about which the blades may rotate. Anglepieces I1 and I8 are secured to the frame to form abutments againstwhich the outside blades I I and I3 rest when closed and serve both asstops for the blades and as a means to close the opening more tightly.The longitudinal edges of the blades are so formed as to interlock withthe adjoining blade.

Actuating brackets I9, 20, and 2I are secured to blades II, I2, and I3by any suitable means as by riveting as at 22, 23, and 24. As shown inFigure 1 these brackets are so shaped that when the blades are in theiropen position, as shown in'dotted lines, the actuating rod 25 Will clearthe edges of the blades. As thus far described the damper is ofconventional construction.

The damper blades are actuated simultaneously by actuating rod 25 whichis pivotally connected to brackets I9, 20, and 2| by trunnions 26, 21,and 28. Rod 25 while 0f sufficient diameter not to buckle in operationis nevertheless rather ilexible.

Figures 2 and 3 illustrate the manner in which the actuating bracketsare attached to rod 25. Trunnion 21 passes through holes 30 in bracket20, the holes being suillciently larger than the .trunnion to permitfree rotation. Rod 25 passes through hole 3| in trunnion 21 andissecured therein by set screw 29.

With the bracket, trunnion and rod as described it is only necessary toloosen all the set screws, close all the blades so that they all closeperfectly, and then tighten up the set screws. 'I'he adjustment of thedamper is complete. By this arrangement, it Will be apparent that lesscare need be taken in the manufacture of the damper than for dampers ofordinary construction thereby reducing the cost of the damper While atthe same time insuring proper operation o! the damper afterinstallation.

By making rod 25 light and exible, inaccuracies of manufacture or slightmisalignment of the parts due to shipping and handling will not causethe mechanism to be sti in its operation. Ii' trunnion 21 is located aslightly greater distance from pivot rod I5 of blade I2 than the othertrunnions 26- and 28 are from the pivot points of their blades, rotationof the blades will result in trunnion 21 traveling in a greater arc thantrunnions ,.26 and 28. Then, if the trunnions were in line in the firstposition, rod 25 will dex on movement away from this position. A similarresult will occur if the effective lever arms of the various trunnionsabout their associated blade pivots are not parall'el. Since rod 25 isof small diameter withrespect to the distance between trunnions it willflex easily causing little binding or friction.

It will be seen that a damper mechanism has been provided which iseasily adjusted on thejob to close tightly, which is smooth and easy inoperation, and which is economical to manufacture because extremeaccuracy of construction is not required.

While one embodiment of the invention has been described it is to beunderstood that it could take other forms apparent to those skilled inthe art and should be limited only by the appended claims and prior art.

I claim as my invention:

1. In a damper mechanism, in combination, a damper frame adapted to bepositioned in a passage through which the flow of medium is to becontrolled, a plurality of damper blades pivotally mounted in said frameand associated with each other in a manner to cooperate with each otherin controlling the ow of medium, a bracket member attached to eachdamper blade, each bracket member extending beyond the edgeof itsassociated damper blade, all of the bracket 'members being in alignment,and a connecting member attached to each bracket member for actuatingsaid damper blades in unison, said connecting member comprising acontinuous exible rod adapted to be stressed longitudinally in bothtension and compression to thereby actuate said damper blades in eitherdirection, flexing of saidA connecting member during movement of saiddamper blades compensating for irregularities in construction of thedamper mechanism and preventing binding of said blades by saidconnecting member.

2. In a damper mechanism, in combination, a damper frame adapted to bepositioned in a passage through which the iiow of medium is to becontrolled, a plurality of damper blades pivotally mounted in said frameand associated with each other-in a manner to cooperate with each otherin controlling the flow of medium, a bracket member attached to eachdamper blade, each bracket member extending beyond the edge-of ,itsassociated damper blade, all of the bracket members being in augment, aconnecting member attached to'each bracket member for actuating saiddamper blades in unison, said connecting member comprising a continuousexible rod adapted to be stressed longitudinally in both tension andcompression to thereby actuate said damper blades in either direction,flexing of said connecting member during movement of said damper bladescompensating for irregularities in construction of the damper mechanismand preventing binding of said blades by said connecting member, andmeans for individually adjusting each of said bracket members relativelyto said connecting member. Y

3. In a damper mechanism, in combination, a damper frame adapted to bepositioned in a passage through which the flow of medium is to becontrolled, a plurality of damper blades pivotally mounted in said frameand associated with each other in a manner to cooperate with each otherin controlling lthe ow of medium, a bracket member attached to eachdamper blade, each bracket member extending beyond the edge of itsassociated damper blade, all of the bracket members being in alignment,a trunnion carried by each bracket member, a connecting member passingthrough each trunnion for actuating said damper blades in unison,adjustable means for securing said trunnions to said connecting member,said connecting member being flexible and being adapted to be stressedlongitudinally in both tension and compression to thereby actuate saiddamper blades in either direction, flexing of said connecting memberduring movement of said damper blades compensating for irregularities inconstruction of the damper mechanism and preventing binding of saidblades by said connecting member.

4. In a damper mechanism, in combination, a damper frame adapted to bepositioned in a passage through which the ow of medium is to becontrolled, a plurality of damper blades pivotally mounted in said frameand associated with each other in a manner to cooperate with each otherin controlling the flow of medium, a bracket member attached to eachdamper blade, eachl in either direction, flexingl of said connectingmember during movement of lsaid damper blades compensating forirregularities in construction of the damper mechanism and preventingbinding of said blades by said connecting member.

lJOHN M. LARsoN.

